need some guidence about power amplifiers and matching techniques...

[ram@419]

hai every one ....
what are the important parameters to be observed while selecting a FET for power amplifier.
which type of power amplifier to be selected for max power i,e class A,B,C....
WHICH TYPE OF AMPLIFIER TO BE SELECTED I,E WHETHER INTERNALLY MATCHED OR EXTERNAL MATCHING AMPLIFIERS....
PLEASE PROVIDE ME THE BASIC IDEA ABOUT POWER AMPLIFIERS AND ITS MATCHING TECHNIQUES

 

[tony_lth]

What is your requirements of power anp?
If you can find internally matched, that's better. If you can't, you must calculate the matched circuits.

 

[BigBoss]

Nowadays, nobody wants to read and learn something..even on the internet that is a universe of knowledge... tons of books, billions of app. notes... countless knowledge..
Everything will be ready to use like a pill..
Take it and no pain...
What a wondeful world...!!!

 

[UKnowWhat]

I understand your sentiment BigBoss for plenty of people who only want to have quick ready-made answers without bothering to invest any sweats. However, the internet is like an ocean of knowledge and it's very daunting to tumbling forward if one doesn't have an inkling feeling of what to look for. So ...

For start, it all depends on your power and bandwidth requirement. Internal matching will guarantee to work at frequencies specified but you may have a hard time to increase your bandwidth outside of their specification, if you don't understand the input Q factor of the chosen transistor. Class A design needs transistor having more power than class AB, B etc because of class A efficiency realistically is at 33%. And the type of modulation also affects your device' selection, so on, so forth.

So grab some books & app notes, like Radio Frequency Transistors written by Norman Dye and Helge Granberg, arguably one of the best RF Engineers during my time. This book will probably answer most of your basic questions that you've listed above, and more. Philips app note SC19, RF Transmitting transistor and power amplifier fundamentals is also a very good app note.